KH400 Starting problems
Kawasaki’s KH400 sometimes gets hard to start when the engine is warm. KH400’s have CDI (capacitor discharge ignition) systems which are generally great because the timing stays fixed and there are no points to wear out. However, the electronics, particularly when they are nearly 40 years old, are susceptible to failure.
My KH400 is an interesting example because I bought it in 2012 with only 150 miles on it - 36 years after it was built! In January 2014 I noticed the electrical system was getting weak. It didn’t generate enough power to recharge the battery with the headlight on. I wondered how the coils could break down with so little mileage. Apparently all it takes is time for the insulating varnish to break down on the copper wires, creating shorts and reducing the charging ability. I had the stator coils rewired and that problem went away.
Lately the bike was taking lots of kicks to get started, sometimes 10 or more. Jim Hobbs at Lakeland Services sells a replacement parts for Kawasaki triples. I gave him a call and explained the bike doesn’t have a hard time starting when warm, but it does when the engine is cold. He said the hard starting problem whether the engine is warm or cold is generally caused by a failing low speed coil. Okay I want it fixed now so I went and ordered one. Two days later the part arrived in the mail.
Here’s the new coil. It’s pretty small.
And here’s the left side of the KH400 with the stator cover and flywheel removed. If you need to remove the flywheel, read the KH400 flywheel removal post. The high speed coil is mounted in front of the low speed coil.
Now we get into the nitty gritty. First, remove the two long screws that hold the two coils onto the plate. See the aluminum spacers between the two coils? Remember to include them when the coils are being reassembled. The low speed coil has epoxy covering the terminals. The epoxy can be cracked with needle nose pliers and then the wires can gently be removed. Two white wires attach to the left terminal and a black wire attaches to the right terminal. Here’s another picture.
In the picture above you can see one white wire and one black wire, these are coming off the high speed coil and attaching to the low speed coil. Another white wire is behind the low speed coil. If you are like me and not an expert on this stuff, take it one step at a time.
Next, get out the soldering iron and attach the white and black wires to the terminals on the new coil. The wires might need to be lengthened. I used some copper strands and ran them through the terminal for the white wires, then soldered the two wires, one to each side of the strands. Insulation - it’s hard to get in there with heat shrink so I used fast drying epoxy to cover the exposed strands and prevent shorts.
Those long screws that hold the coils on are pretty fragile. Both screws got twisted and damaged when I removed them. Luckily, City Mill, the local hardware store in Kaimuki, had replacement screws - M4 x 40mm plus a lockwasher for each screw. They were a little longer than the original screws so I cut a few millimeters off each of them with an angle grinder.
Here we are with the high and low speed coils reinstalled. The other two coils are the stator coils for the charging system.
Next step, install the flywheel and the engine cover. Oh yeah, and reconnect the battery (I disconnected it at the beginning of the install). Three kicks and the motor was running. After the bike cooled I tried again and it started with one kick. The low speed coil replacement fixed the problem! I’ll be back on the Oahu’s roads tomorrow.